Measured consumption is greater than the nominal value on LPC54608 Evaluation board

I need my board to maintain very low power consumption when idle. The deep sleep mode is an ideal status. But my measured current is about 400uA while the nominal value in the data sheet "LPC546xx" is 23uA. I have spent much time to calibrate it with little improvement. Here is the my configuration to board. If anybody can help me, I will be very grateful.

Configure all pins as GPIO with pull-up resistor disabled in the IOCON block.

Configure GPIO pins as outputs using the GPIO DIR register.

Write 1 to the GPIO CLR register to drive the outputs LOW.

All peripherals disabled.

call the function "POWER_EnterDeepSleep(APP_EXCLUDE_FROM_DEEPSLEEP);" only keeping all RAM active.

insert a multimeter at JP4 between pins 5 and 6 to measure the LPC546xx VDD input current.

I am testing with the evaluation board marked with 'LPCXpresso546xx Rev C'. And the demo code was put in the attachment. I could get current 270uA in 3.3V Vdd so far, but it is seem to still a long way to value on data sheet.

I'm about to do some more testing on a new LPC54606 board I have, but so far all my LPC54608 boards have had the same current consumption, and I'm not able to get to the values in the datasheets (far from)

The problem in the post is very similar to what I encountered. I inspired by your conversation and made the power consumption lower to 270uA on evaluation board. Could you tell me how much current measured on LPC546xx evaluation board?

I am very grateful to you for your dedication on this issue. If you have any idea, please note me.